GnT V-Catalyzed N-glycan Products are not increased in Hepatomas

Abstract

Sugar chains envelop the vast majority of the cell surface and thus have been considered to play pivotal roles in cell-to-cell and cell-to-extracellular matrix interactions. Recent studies have shown that expression of N-acetylglucosaminyltransferase (GnT) V is induced in hepatomas, and high-branched N-linked sugar chains play important roles in carcinogenesis and metastasis. However, the precise structural changes have not yet been studied in detail. Here, we compared sugar chains expressed in normal mouse liver, regenerating liver, three mouse hepatoma cell lines and Hepa 1-6-related tumors obtained by inoculation of Hepa 1-6 cells into liver or subcutaneous tissue of BALB/c nu/nu mice. The products of GnT V were found to be present in similar proportions in the mouse liver and in hepatomas, while there was a big difference in the amount of GnT IV products in these organs. Normal mouse liver and regenerating mouse liver contained small amounts of sugar chains produced by the action of GnT IV, while such chains were abundant in hepatoma cell lines and in Hepa 1-6-related tumors. Analysis of N-linked sugar chains in human livers and in hepatocellular carcinoma (HCC) revealed that both GnT IV and GnT V products are present in human liver, but their total content did not change during malignant transformation. Thus there was no increase in GnT V N-glycan products in hepatoma tissues in the mouse model or in humans.